For the short term, that means being relatively frugal to recover from under-budgeting for this year's taxes (and for the extension of the recent trip) so as to cover the trip (although about half of my hotel is already paid for, as is my membership, but I'll need to pay for the rest of the hotel/lodging, the plane ticket, and incidentals), and my quarterly taxes.
For the longer term:
Need to figure out exactly when I'm going. I'm thinking of shifting most of the trip to before the convention, even though that means more time spent in August and less in September, so the weather will probably suck more. But the next two items kinda dictate that:
I want to climb Mt. Fuji, so I need to think about that. Which includes researching access and amenities (huts, I think, if I plan to see the top at dawn), and figuring out exactly how I'm going to deal with suitcase/backpack/hiking gear, etc.
I want to see a Rakuten Eagles game. Which might be just barely possible, since they're playing in Chiba the week before the convention, I believe. Also want see another game in Yokohama, maybe (albeit less so if I see a game in Chiba), but there's nothing in Yokohama that particularly needs to be planned for ahead of time, so I'm not going to worry so much about that. Outside possibility (if I take the north option instead of the south option wandering around) -- see a game in Sendai proper.
I need to figure out where else in Japan I plan to go besides Fuji-san and Yokohama, and whether or not it makes sense to get a rail pass, and for how long, etc. -- was originally thinking Takayama and Chuubu Sangaku Kokuritsu Kouen ("Japanese Alps" National Park) and Nagoya (you can't really get to Takayama without going through Nagoya anyway) -- may skip Nagoya, though (August, yikes). Alternately -- given the time of year -- perhaps it makes more sense to go north again this time, perhaps back to Akita for the things I missed (Tazawako, hiking in Kakunodate), and up through Aomori and a bit of Hokkaido. I'm probably going to give that serious consideration, especially with already packing the hiking gear for Fuji-san and such.
Also, need to make sure that whatever my schedule is, I miss obon.
At any rate, I'm not making decisions today, or probably for a couple months yet.